As used herein, "aluminum" means aluminum and aluminum based alloys, and "continuous casting" includes casting ingots of limited length.
The most widely used commercial practice of vertical continuous casting of aluminum is to feed aluminum vertically down along a central axis of a mold to a level control device having outlets through which the molten aluminum passes at the top of an ingot being cast in the mold. The mold has vertical, chilled, metal walls, and the ingot emerging beneath the mold is directly chilled by water spray. This system is disclosed in Ennor U.S. Pat. No. 2,301,027, and is commonly referred to as "DC Casting."
One of the variants of DC casting is the casting system illustrated in Moritz U.S. Pat. No. 2,983,972. The Moritz patent teaches the use of insulation within a mold to control the level of the "freeze line," and also teaches feeding molten aluminum from the side of the mold, to reduce turbulence and avoid some of the practical problems associated with use of a vertical feed system required in practice of conventional DC casting systems. The Mortiz casting system is still in successful commercial use, but wider adoption of this system has been hampered by difficulties in using available insulating materials, which have limited service life and have had a tendency to break off to appear as undesirable inclusions in the ingots or to cause ingot surface defects such as tearing.
A great many other variants in continuous casting practices have been tried and disclosed, but the art has continued looking for better combinations of features to provide an improved continuous casting system which more nearly satisfies commercial requirements than what has been generally used heretofore. It is an object of this invention to provide such a system.